H3C Technologies H3C S3600 Series Switches - Manual (Page 795)

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fabric and downloads the software used by the device in the current fabric to the local device. Then
the device will automatically restart and be added to the fabric.
z If the fabric name of the local device is inconsistent with that of the device in the fabric, the system
automatically ignores the inconsistency check of the fabric name and adds the device to the fabric.
Then the system automatically synchronizes the configurations to the device with the smallest unit
ID and changes the fabric name.
With the above operations completed, the device can be added to the fabric and work normally.
z You need to enable the IRF automatic fabric function on all the devices including the candidate
switch in the fabric to enable the candidate switch to download software and discovery neighbors
and thus be added to the fabric normally.
z If the candidate switch is going to download software from a unit in an IRF fabric, you are
recommended to set the ID of the unit to 1 to make the candidate switch download the software of
correct version.
How IRF Works
When a fabric is established, the devices determine their respective roles in the fabric by comparing
their CPU MAC addresses. The device with the lowest CPU MAC address is elected as the master and
the other devices are slaves.
After the election, the fabric can operate normally. The following three functions of IRF can provide
simple configuration mode, enhanced network performance and perfect redundancy backup
mechanism for users.
z The S3600-SI series Ethernet switches support basic IRF fabric feature, that is, Distributed Device
Management (DDM) function and Distributed Link Aggregation (DLA).
z The S3600-EI series Ethernet switches support enhanced IRF fabric feature, including DDM,
Distributed Redundancy Routing (DRR) and Distributed Link Aggregation (DLA).
DDM
DDM is a new device management mode provided by IRF. In normal cases, a fabric can be considered
as a single device. You can manage the entire fabric by logging onto any device in the fabric with
different logging modes. The devices in the fabric synchronize their configurations by exchanging
packets, thus ensuring stability of the fabric.
FTM program uses Unit ID, or device ID to distinguish between the devices in a fabric when you
manage them. On initialization of the IRF function, each device considers its Unit ID as 1 and after a